Reply To: Miscellaneous Electric Tips

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“can u explain watts, amps, and volts“

Think of a stream 10 feet wide, in which the water runs at 5 miles per hour.

Let’s say that every second 100 gallons of water flow past a specific point.

Increasing the speed of the water to 10 miles per hour would be analogous to increasing the voltage.

Widenening the stream to 20 feet, while keeping the flow at 5mph would be analogous to increasing the amperage.

In both cases, we will now have 200 gallons per second flowing past that point.

Wattage is the total electric power. You derive this number by multiplying amps times volts.

The amperage needed by a hundred-watt bulb that uses standard U.S. household current can be derived as follows: 110(volts) * ?(amps) = 100(watts). The amperage required is .90909 amps.

A transformer that raises or lowers voltage is simply changing the voltage and amperage numbers, but the wattage remains the same.

A couple of unrelated side points:

a)

A water-heating system’s radiator will need two pipes; one to bring the hot water and the other to take the water back to the boiler for reheating.

A steam-heat system will only have one pipe; to bring the hot steam. As the heated steam enters the radiotor, the cold air escapes thru the valve located on the opposite end of the radiator. Once the hot steam reaches the valve, an expanding part in the valve pops up and cuts off the flow of escaping steam. Once the steam cools, it condenses into water, and trickles out of the radiotor thru the same pipe as the steam entered. It is then returned to the boiler for reheating.

Common problems with steam heat systems are:

-Valves that don’t cut off when the hot steam hits them. If you see steam escaping from a rediator’s valve, try tapping it gently to see if this will jar the mechanism into closing.

-Steam leaks along the pipe’s joints.

(the above two problems can result in leaking steam, dripping water, and the boiler running dry too quickly).

-A radiator’s air release valve installed on the same side of the radiator as the steam pipe. This causes the valve to close before hot steam has entered the entire radiator, and the room will not heat (or take too long to heat).

b)

A/C current doesn’t really run thru a capacitor, but for all practical purposes it’s as if it does. A capacitor prevents more than a certain amount of current from building up on each side of its plates. With DC current, that amount builds up, and then no more can get by. With AC current, since the electrons are basically vibrating back and forth (rather than moving in one direction), nothing builds up on the capacitor’s plates.

c)

“Pashuteh Yid”s theory of attaching a large metal plate to a bulb, on the side opposite the hot wire, and seeing the bulb light up slightly is correct (at least with AC; I never tried it with DC). I know this because I once fixed a circuit where the neutral had detatched from the neutral bus bar in the breaker panel, and when a light switch was flipped on for that line, it glowed dimly.